Circular stapling device

Abstract

A circular stapling device includes a manually operated trigger ( 24 ) that is adapted to allow staple formation to occur prior to cutting of tissue during a single actuation of the firing trigger ( 24 ). The stapling device ( 10 ) minimizes stretching and movement of tissue during staple formation to improve staple formation. The stapling device ( 10 ) also reduces the amount of force required to move the firing trigger ( 24 ) through a firing stroke by separating the staple formation and tissue cutting functions of the stapling device ( 10 ) to reduce stress on a clinician's hand during actuation of the stapling device ( 10 ).

What is claimed is: 
     
       1. A circular stapling device comprising:
 a handle assembly including a firing trigger; 
 an elongate body supported by the handle assembly, the elongate body having a proximal portion and a distal portion; 
 a shell assembly supported on the distal portion of the elongate body, the shell assembly including a shell housing defining a cavity, a staple cartridge supported on the shell housing, a pusher defining a longitudinal bore, a knife carrier movable within the longitudinal bore, and a knife supported on the knife carrier, the staple cartridge supporting a plurality of staples and the pusher being movable within the cavity of the shell housing from a retracted position to an advanced position to eject the plurality of staples from the staple cartridge; and 
 an anvil assembly supported on the distal portion of the elongate body and being movable in relation to the shell assembly between open and clamped positions; 
 wherein the knife carrier engages the pusher and is movable between a retracted position and an intermediate position to move the pusher from its retracted position to its advanced position and subsequently movable from its intermediate position to an advanced position independently of the pusher to advance the knife to cut tissue. 
 
     
     
       2. The circular stapling device of  claim 1 , wherein the firing trigger is coupled to the knife carrier such that movement of the firing trigger through an actuation stroke moves the knife carrier from its retracted position to its advanced position. 
     
     
       3. The circular stapling device of  claim 2 , wherein the firing trigger is manually movable through the actuation stroke. 
     
     
       4. The circular stapling device of  claim 1 , wherein the knife carrier includes at least one tab, the at least one tab being movable from a first position engaged with the pusher to translate distal movement of the knife carrier to distal movement of the pusher, to a second position to allow distal advancement of the knife carrier independently of the pusher. 
     
     
       5. The circular stapling device of  claim 4 , wherein each of the at least one tabs is supported on a resilient arm. 
     
     
       6. The circular stapling device of  claim 5 , wherein the resilient arm supporting each of the at least one tabs is supported in cantilevered fashion to the knife carrier. 
     
     
       7. The circular stapling device of  claim 5 , wherein the shell assembly includes a housing that includes at least one longitudinal rib, the at least one longitudinal rib being positioned to engage the resilient arm supporting each of the at least one tabs to retain each of the at least one tabs in the first position as the pusher is moved towards its advanced position. 
     
     
       8. The circular stapling device of  claim 1 , wherein one of the pusher and the knife carrier includes a breakable ring and the other of the pusher and the knife carrier includes an annular projection that is positioned to engage the breakable ring. 
     
     
       9. The circular stapling device of  claim 8 , wherein the breakable ring is adapted to fracture when the pusher nears its advanced position to facilitate movement of the knife carrier independently of the pusher. 
     
     
       10. A shell assembly comprising:
 a shell housing defining a cavity; 
 a staple cartridge supported on the shell housing, the staple cartridge supporting a plurality of staples; 
 a pusher defining a longitudinal bore; 
 a knife carrier movable within the longitudinal bore of the pusher; and 
 a knife supported on the knife carrier; 
 wherein the pusher is movable within the cavity of the shell housing from a retracted position to an advanced position to eject the plurality of staples from the staple cartridge, and the knife carrier engages the pusher and is movable between a retracted position and an intermediate position to move the pusher from its retracted position to its advanced position and subsequently movable from its intermediate position to an advanced position independently of the pusher to advance the knife to cut tissue. 
 
     
     
       11. The shell assembly of  claim 10 , wherein the firing trigger is coupled to the knife carrier such that movement of the firing trigger through an actuation stroke moves the knife carrier from its retracted position to its advanced position. 
     
     
       12. The shell assembly of  claim 10 , wherein the knife carrier includes at least one tab, the at least one tab being movable from a first position engaged with the pusher to translate distal movement of the knife carrier to distal movement of the pusher, to a second position to allow distal advancement of the knife carrier independently of the pusher. 
     
     
       13. The shell assembly of  claim 12 , wherein each of the at least one tabs is supported on a resilient arm. 
     
     
       14. The shell assembly of  claim 13 , wherein the resilient arm supporting each of the at least one tabs is supported in cantilevered fashion to the knife carrier. 
     
     
       15. The shell assembly of  claim 13 , wherein the shell assembly includes a housing that includes at least one longitudinal rib, the at least one longitudinal rib being positioned to engage the resilient arm supporting each of the at least one tabs to retain each of the at least one tabs in the first position as the pusher is moved towards its advanced position. 
     
     
       16. The shell assembly of  claim 10 , wherein one of the pusher and the knife carrier includes a breakable ring and the other of the pusher and the knife carrier includes an annular projection that is positioned to engage the breakable ring. 
     
     
       17. The shell assembly of  claim 16 , wherein the breakable ring is adapted to fracture when the pusher nears its advanced position to facilitate movement of the knife carrier independently of the pusher. 
     
     
       18. A shell assembly comprising:
 a shell housing defining a cavity; 
 a staple cartridge supported on the shell housing, the staple cartridge supporting a plurality of staples; 
 a pusher defining a longitudinal bore, the pusher being movable within the cavity of the shell housing from a retracted position to an advanced position to eject the plurality of staples from the staple cartridge; 
 a knife carrier movable within the longitudinal bore of the pusher; and 
 a knife supported on the knife carrier; 
 wherein the knife carrier is releasably coupled to the pusher and movable independently of the pusher to cut tissue after staple formation. 
 
     
     
       19. The shell assembly of  claim 18 , wherein the knife carrier includes at least one tab, the at least one tab being movable from a first position engaged with the pusher to translate distal movement of the knife carrier to distal movement of the pusher, to a second position to allow distal advancement of the knife carrier independently of the pusher. 
     
     
       20. The shell assembly of  claim 18 , wherein one of the pusher and the knife carrier includes a breakable ring and the other of the pusher and the knife carrier includes an annular projection that is positioned to engage the breakable ring.